Refactor code

src/Day11.hs

@@ -0,0 +1,34 @@
+module Day11
+  ( day11_1,
+    day11_2,
+  )
+where
+
+import qualified Data.Map.Strict as M
+
+blinkStone :: (Int, Int) -> [(Int, Int)]
+blinkStone (0, n) = [(1, n)]
+blinkStone (s, n) =
+  let ss = show s
+      nDigit = length ss
+   in if even nDigit
+        then zip (map read [take (nDigit `div` 2) ss, drop (nDigit `div` 2) ss]) [n, n]
+        else [(s * 2024, n)]
+
+blink :: Int -> M.Map Int Int -> M.Map Int Int
+blink 0 m = m
+blink n m = blink (n - 1) $ M.fromListWith (+) $ concatMap blinkStone $ M.toList m
+
+day11_1 :: IO ()
+day11_1 = do
+  contents <- M.fromListWith (+) . flip zip (repeat 1) . map read . words <$> readFile "input/day11.txt"
+  putStrLn $
+    "Day 11, Puzzle 1 solution: "
+      ++ show (M.foldl (+) 0 $ blink 25 contents)
+
+day11_2 :: IO ()
+day11_2 = do
+  contents <- M.fromListWith (+) . flip zip (repeat 1) . map read . words <$> readFile "input/day11.txt"
+  putStrLn $
+    "Day 11, Puzzle 2 solution: "
+      ++ show (M.foldl (+) 0 $ blink 75 contents)